Diesel fuel



atente II MESH 1 :1 ohn H. Mcfilraeken and w Wcodbury, N. 5.,

Oil Gompm Inc New York No Bra.

r r rated, a corporation gnors to Socony-t7a I i lpplicationmecber is, race,

Serial lilo. 5145M I a claims. ei. ie-sv) This invention relates to fuels for internal com- I bastion engines of the Diesel or compression ignition type and is more particularly concerned with the improvement of such fuels by the addition thereto of a characterizing agent. I

It is necessary for the maximum efilciency of a Diesel engine that the ignition of'the iuel be grade hydrocarbon mixtures may be improved sumciently to render them available as fuels.

Some of the desirable characteristics of a Diesel fuel improving agent apart from that of increasing the cetane number of thefuel are relative 25 insolubility in water and chemical stability in the presence or the same because of the common practice to store fuelsin contact with water. It should be soluble in the fuel to the extent of 5 or 10 per cent by weight. Greater solubility isdeslrable ii: thd additive is to be marketed in the form of a concentrate in fuel oil. The addidve should not cause the formation of sediment or sludge-factors which might cause depreciation 'like materials, which substantially reduce the operating eiiiciency ofthe engine. Correspondingly, other compounds may also improve the ignition qualityuof a Diesel fuel but they are generaliy so corrosive in character that the metal I parts of the engine with which the fuel is in contact are seriously corroded; in this way the em-v ciency of the engine is also reduced.

This invention is predicated upon discovery that gem-dinitropropanes-dinitropropanes having both nitro groups attached to the same carbon atom-are highly efiective in improving the ignition quality of 8. Diesel fuel. The improving agents of the present invention, therefore, are l,land 2,2-dinitropropancs Accordingly, the present invention contemplates Diesel fuel con-. taining a minor proportion of such compounds for the aforesaid improvement. The present invention also contemplates the development oi a I proved. Similarly,- the ignition quality of low 2a method for accelerating the spontaneous ignition of liquid hydrocarbon fuels in compression ignition engines which method is characterized y the admixture of the aforesaid dinitropropanes with the fuel prior toits ignition. a While the gem-dinitroparamns as a class are particularly effective Diesel fuel improving agents as described in copending application Serial No.

i is superior to other gemof the octane number of the fuel and fouling or e clogging of the injection equipmentof' the engine. The additive initially, as well as on combustion of the fuel, should not yield any products which are corrosive to the engine parts with which they come in contact.

Of the compounds previously proposed for use as Diesel fuel improving agents it may be said that many of them suffer from one or more ondesirable characteristics, such as poor storage stability in Diesel fuel, excessively high degree of corrosivity to metals, tendency to form in-- soluble deposits with the fuel, eta. Characteristics such as the foregoing are important in the proper selection of a Diesel fuel improving agent and are to be avoided as much as possible. For example, although certain compounds may enhanc the ignition duality'of a. Diesel fuel, they are generally, characterized by a low degree of stability on storage .in the fuel and give rise to the formation of undesirable 11.. and sludge- 405,133, filed AugustZ, 1941, by one of the present inventors, John H; McCraciren, it has now been found that 2,2-dinitropropane is outstan; It

tropara in a greater enhancement of the ignition quality of a Diesel fuel and in a greater storage stability in such a fuel. I r v With regard to methods of preparation of the gem-dinitropropanes, the method described by v. Meyer and Locher, Ann. 180, 133 (187 6) is satisfactory for the preparation of 2,2-troinvention is not concerned with or limited by the procedure by which the gem-dinitropropanes are prepared. Inasmuch as the gem-dinitropropanes and their methods of preparation are well known a it is mlieved unnecessary to describe their prep-- 'aration in this application.

The outstanding eiiectiveness of 2,2-dinitropropane in improving the ignition quality of a Diesel fuel is demonstrated by comparative results of a fuel blank and of typical iuel blends obtained inthe following manner. A base stock a commonly known as a No. 2 fuel oil which-has a propane, and the method proposed by ter Meer,

flash point of 172 (3., an A. P. I. gravity 0139.8. an aniline point of 160.5" C. and a cetane number of 55.0 was used in all tests. The ignition quality of the base stock and of the fuel blends was determined by comparison with a standard reference fuel in a C. F. R. engine using the ignition I delay method. The value obtained in this test is expressed as the cetane number" which is the per cent by volume of cetane in a blend of cetane and alpha methyl naphthalene having the same combustion characteristicsas the sample under test. (See Proc. Am. Soc. TestingMaterials. volume 36, I, 418 (1936).)

The results obtained in the foregoing test with fuel blends containing. the preferred gem-dinitropropane2,2-dinitropropane-and other representative compounds of the broad class of gemdinitroparaffins are tabulated in the table below.

It will be apparent from the foregoing results that 2,2-dinitropropane is outstandingly effective in decreasing theignition delay period of 9, Diesel fuel. propane is substantially superior to other gemdinitroparamns, such as dinitromethane, 1,1,-dinitroethane and 1,1-dinitroheptane. For example 0.5% by weight of 2,2-dinitropropane increased the cetane number of the fuel by 9.9 units, whereas the same-amount of 1,1-d initroethane It will also be apparent that 2,2-dinitro-,

and of dinitromethane rendered increases of only 8.0 units and 5.0 units, respectively.

The gem-dinitropropanes hereinafter claimed in this invention may be used in Diesel fuel in varying amounts. For example, ftoeflect satisfactory improvement of the ignition quality of a Diesel fuel, as indicated by the foregoing results, amounts varying from about 0.1 per cent to about 10.0 per cent may be used. Larger amounts may be used, however, to provide Diesel fuel concentrates, which are also contemplated herein. In

thelatter, the amount of gem-dinitropropane 'may be increased beyond the aforesaid percentage rangeto provide such concentrates as fuels saturated with a gem-dinitropropane. It is to be further understood that when the terms "Diesel fuel" or Diesel type fuel, etc., are used herein reference is made to any liquid hydrocarbon adapted for use in any compression ignition engine.

We claim:

1. An improved Diesel fuel having in admixtur therewith a .minor proportion, suflicient to decrease the ignition. delay period of the fuel, of

2,2-dinitropropane.

2. An improved Diesel fuel having in admixture therewith between about 0.1 per cent and about 10.0 per cent of 2,2-dinitropropane.

3. The method of accelerating the ignition of a liquid hydrocarbon fuel in an engine where the fuel is injected into compressed air in the engine cylinder and ignites spontaneously therein, which comprises admixing with the fuelhprior to its injection into the cylinder, 9. minor proportion, of

. 2,2-dinitropropane.

4. A Diesel fuel concentrate comprising a major proportion of a liquid hydrocarbon fuel and a minor proportion of 2, 2-dinitropropane.

JOHN H. mmcm. EDWIN M. NYGAaRD. 

